##Readme
Add yourself to the www-data group and set the setgid bit on the /var/www directory such that all newly created files inherit this group as well.
sudo gpasswd -a "$USER" www-data Correct previously created files (assuming you to be the only user of /var/www):
sudo chown -R "$USER":www-data /var/www find /var/www -type f -exec chmod 0660 {} ; sudo find /var/www -type d -exec chmod 2770 {} ;